1. Field of the Invention
The present invention relates to a method and an apparatus for carrying a workpiece from one place to another.
2. Description of the Background Art
Conventionally, there have been various types of apparatuses for carrying a relatively small workpiece such as a semiconductor chip by picking up the workpiece at a supply station and carrying it over to a prescribed position for the next manufacturing step.
For instance, as an example of an apparatus which carries the workpiece while holding it and releases the workpiece at a prescribed position, there is that which is disclosed in Japanese Patent Application Laid Open No. 62-114290.
In this conventional apparatus for carrying workpiece, a vertically movable suction head provided on a circumference of a rotatable table is lowered at a suction station after the table is stopped there, and then raised after the workpiece such as a chip is sucked. Then, the table is rotated for a prescribed angle to reach an installation station while the workpiece is sucked by the suction head. Then, the suction head is lowered and the workpiece is released at the installation station after the table is stopped there, so as to install the chip on a printed substrate placed at the installation station, and thereafter the same operation is repeated.
However, such a conventional apparatus for carrying workpiece has a drawback in that the rotation of the table must be stopped at a time of picking up the workpiece by the suction head and at the time of the releasing the workpiece from the suction head so that the rotatable table is required to carry out an intermittent rotational motion, which inevitably incorporates time losses during stopping of the rotatable table and is therefore less preferable from a point of view of the efficiency in the workpiece carrying operation.
Moreover, such a conventional apparatus for carrying a workpiece is a highly specialized apparatus in which the carrier passage for the workpiece is limited on the circumference of the rotatable table, so that applicability of the apparatus is severely limited.
In addition, in such a conventional apparatus for carrying a workpiece, the workpieces to be carried by the apparatus are required to have the identical size. Although this drawback can be partially resolved by changing the suction head according to the size of the workpieces to be carried, it is still impossible to deal with workpieces of mixed sizes.
Furthermore, in such a conventional apparatus for carrying a workpiece, it becomes impossible to achieve proper installation of the workpiece with a correct orientation when the workpiece is picked up by being sucked by the suction head at the suction station in an incorrect orientation deviating from a correct one.